Porcelain fused to metal restorations offer the dental practitioner an abrasion resistant, permanent type of esthetic veneer for dental castings. However, if porcelain "peel off" or fracture should occur, the repair of the restoration is difficult, costly, and time consuming. Such failure of the porcelain to metal bond occurs more frequently today due to the numerous new types of alloys and associated techniques available. This program is complicated by the fact that we do not have a satisfactory method of testing the true bond strength of porcelain fused to metal. In order to evaluate the compatibility of a porcelain-metal system, the bond strength must be measured in absolute values of tensile, compressive, and shear stress. This can only be accomplished by a test for which the stress distribution at the porcelain-metal interface is known. Present tests are not so defined, and extraneous variables (such as sample size) influence the test results. The authors are using a mechanical test for which the stress analysis is known and the samples are easy to prepare. The test places the sample under torsional loading and allows for independent variance of the tensile stress in the porcelain and the shear stress at the interface. This allows for determination of an absolute shear bond strength of a porcelain metal system. Pilot studies by the authors have sustantiated the feasibility of this test on porcelain-metal systems. It is the aim of this research project to substantiate the use of this mechanical test on porcelain-metal systems, and to evaluate the true bond strength of several presently available porcelain-metal systems. This would provide the dental field with necessary data to evaluate and develop porcelain metal restorations with optimum porcelain to metal bonding.